Experimental and simulation research on hollow AZ31 magnesium alloy three-channel joint by hot extrusion forming with sand mandrel

Magnesium alloy is one of the lightest metal structural materials.The weight is further reduced through the hollow structure.However,the hollow structure is easily damaged during processing.In order to maintain the hollow structure and to transfer the stresses during the high temperature deformation,the sand mandrel is proposed.In this paper,the hollow AZ31 magnesium alloy three-channel joint is studied by hot extrusion forming.Sand as one of solid granule medium is used to fill the hollow magnesium alloy.The extrusion temperatures are 230℃ and 300℃,respectively.The process parameters(die angle,temperature,bottom thickness,sidewall thickness,edge-to-middle ratio in bottom,bottom shape)of the hollow magnesium alloy are analyzed based on the results of experiments and the finite element method.The results are shown that the formability of the hollow magnesium alloy will be much better when the ratio of sidewall thickness to the bottom thickness is 1:1.5.Also when edge-to-middle ratio in bottom is about 1:1.5,a better forming product can be received.The best bottom shape in these experiments will be convex based on the forming results.The grain will be refined obviously after the extrusion.Also the microstructures will be shown as streamlines.And these lines will be well agreement with the mold in the corner.

Three-channel CMOS transimpedance amplifier for LiDAR sensor receiver

For time-of-flight(TOF)light detection and ranging(LiDAR),a three-channel high-performance transimpedance amplifier(TIA)with high immunity to input load capacitance is presented.A regulated cascade(RGC)as the input stage is at the core of the complementary metal oxide semiconductor(CMOS)circuit chip,giving it more immunity to input photodiode detectors.A simple smart output interface acting as a feedback structure,which is rarely found in other designs,reduces the chip size and power consumption simultaneously.The circuit is designed using a 0.5μm CMOS process technology to achieve low cost.The device delivers a 33.87 dB?transimpedance gain at 350 MHz.With a higher input load capacitance,it shows a-3 dB bandwidth of 461 MHz,indicating a better detector tolerance at the front end of the system.Under a 3.3 V supply voltage,the device consumes 5.2 mW,and the total chip area with three channels is 402.8×597.0μm2(including the test pads).

Detecting XSS with Random Forest and Multi-Channel Feature Extraction

In the era of the Internet,widely used web applications have become the target of hacker attacks because they contain a large amount of personal information.Among these vulnerabilities,stealing private data through crosssite scripting(XSS)attacks is one of the most commonly used attacks by hackers.Currently,deep learning-based XSS attack detection methods have good application prospects;however,they suffer from problems such as being prone to overfitting,a high false alarm rate,and low accuracy.To address these issues,we propose a multi-stage feature extraction and fusion model for XSS detection based on Random Forest feature enhancement.The model utilizes RandomForests to capture the intrinsic structure and patterns of the data by extracting leaf node indices as features,which are subsequentlymergedwith the original data features to forma feature setwith richer information content.Further feature extraction is conducted through three parallel channels.Channel I utilizes parallel onedimensional convolutional layers(1Dconvolutional layers)with different convolutional kernel sizes to extract local features at different scales and performmulti-scale feature fusion;Channel II employsmaximum one-dimensional pooling layers(max 1D pooling layers)of various sizes to extract key features from the data;and Channel III extracts global information bi-directionally using a Bi-Directional Long-Short TermMemory Network(Bi-LSTM)and incorporates a multi-head attention mechanism to enhance global features.Finally,effective classification and prediction of XSS are performed by fusing the features of the three channels.To test the effectiveness of the model,we conduct experiments on six datasets.We achieve an accuracy of 100%on the UNSW-NB15 dataset and 99.99%on the CICIDS2017 dataset,which is higher than that of the existing models.

磁道钉的磁感应强度实验研究

磁道钉是基于磁信号导航的自动公路系统最重要的道路引导标志。文章介绍了用作磁道钉的永磁材料的主要性能,如剩磁、矫顽力和磁能积及稳定性,并以此为主要内容研究磁道钉的永磁特性;利用三通道高斯计测试不同型号的磁道钉的磁感应强度,包括X、Y、Z方向分量,得到其磁场分布数据及分布曲面图。提出了针对测试区域中任一位置的磁感应强度X、Z分量值,利用整个测试区域的磁感应强度X、Z方向分量数据,得到横向偏差的确定方法。

一种基于高斯计的新型砝码磁参数测量系统

电子比较仪(天平)是基于电磁平衡原理进行工作的,由于砝码与电子比较仪之间产生的相互磁力作用对称量结果具有重大影响,磁性参数满足要求的砝码才能被用于质量测量和量值传递.鉴于目前国际上使用的测量方法和仪器对于低准确度等级或者非圆柱体砝码磁参数的测量效果较差,建立了一种新型的基于高斯计的砝码磁参数测量系统,利用高斯计和计算机对测量系统进行控制以及数据采集和处理,实现了直线、平面、转动等多种测量模式.实验结果表明了该系统的有效性.

对变压器绕组内并联导线间短路点的检查与修复

介绍了运用高斯计来探查变压器绕组内并联导线间短路点,并对故障点进行修复的方法。

Time-delayed bilateral teleoperation using wave variable with prediction in three channel control architecture

This paper proposes a novel method for incorporating wave domain prediction in a three-channel(3CH)architecture,which is the optimal architecture from a transparency point of view,to overcome the poor transparency problem of using the wave variable method in a time-delay teleoperation system.A 3CH teleoperation control architecture is established by selecting parameters of the 4CH architecture sensibly for the system without force sensor in the master side.The communication channel is divided into a two-port model by combining force and velocity information reasonably to extend the wave variable method to a 3CH architecture.Then the I/O signal of the two-port model is transformed into wave variable.A predictor is added to the wave domain of the master side to further improve the transparency of the system,and a regulator is designed to ensure the passivity of the predictor.Experimental results show that the proposed method can guarantee stability and improve the transparency of the teleoperation system with time-delay.

Three-channel dual-wavelength fiber laser based on a digital micromirror-device processor and photonic crystal fiber

A stable three-channel dual-wavelength fiber ring laser is proposed and experimentally demonstrated. The dig- ital mieromirror-deviee （DMD） processor can select and reeirculate any dual waveband from the gain spectrum of the erbium-doped fiber at each channel. The uniform and stable dual-wavelength oscillation is obtained by a highly nonlinear photonic crystal fiber, which causes two degenerate the four-wave-mixing processes. By loading different reproducibility diffraction gratings on the optoelectronic DMD processor, the laser can be operated stably in a three-channel dual-wavelength scheme at room temperature. The power fluctuation of each laser channel is less than -0.02 dB.